Collections refactoring.

1 files changed, 39 insertions, 0 deletions

diff --git a/src/library/scala/collection/TraversableView.scala b/src/library/scala/collection/TraversableView.scala
new file mode 100644
index 0000000000..e5d5400cf9
--- /dev/null
+++ b/src/library/scala/collection/TraversableView.scala
@@ -0,0 +1,39 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id$
+
+
+package scala.collection
+
+import generic._
+import mutable.Builder
+import TraversableView.NoBuilder
+
+/** <p>
+ *    A base class for views of <a href="../Traversable.html"
+ *    target="ContentFrame"><code>Traversable<code></a>.<br/>
+ *    Every subclass has to implenment the <code>foreach</code> method.
+ *  </p>
+ *
+ *  @author Martin Odersky
+ *  @version 2.8
+ */
+trait TraversableView[+A, +Coll] extends TraversableViewLike[A, Coll, TraversableView[A, Coll]]
+
+object TraversableView {
+  class NoBuilder[A] extends Builder[A, Nothing] {
+    def +=(elem: A): this.type = this
+    def iterator: Iterator[A] = Iterator.empty
+    @deprecated("use `iterator' instead") def elements = iterator
+    def result() = throw new UnsupportedOperationException("TraversableView.Builder.result")
+    def clear() {}
+  }
+  type Coll = TraversableView[_, C] forSome {type C <: Traversable[_]}
+  implicit def builderFactory[A]: BuilderFactory[A, TraversableView[A, Traversable[_]], Coll] = new BuilderFactory[A, TraversableView[A, Traversable[_]], Coll] { def apply(from: Coll) = new NoBuilder }
+}